Which statement is correct regarding HF NBDP under GMDSS?

Correct Answer: Option A — Safety communications by direct-printing telegraphy should be in the ARQ mode when communicating with the U.S. Coast Guard or other coast stations on channels that they normally guard.

IMO GMDSS regulations require ARQ mode for safety and distress communications directed to coast stations. ARQ provides error correction through a handshake protocol, ensuring the integrity of transmitted data. This is critical when communicating with coast stations that maintain a dedicated watch on specific frequencies to ensure receipt of safety-related information.